1. Field of the Invention
The invention relates to an output thyristor with at least two electrodes placed on the base area of the cathode side, wherein one of the two electrodes serves as control electrode (ignition or starting gate) and the second electrode serves as the discharge of a current (the generator gate). This invention further relates to use of this kind of thyristor in rectifier circuits in which several thyristors are connected in parallel.
2. Description of the Prior Art
In large plants in the power electronics industry frequently several thyristors must be connected in parallel. It is possible that in unfavorable usage conditions, individual thyristor elements might not ignite or start or might become non-conductive because of low current. Then, with a subsequent increase in current the thyristors connected to the non-conductive thyristor could be overloaded and destroyed. To avoid such accidents, presently relatively expensive measures must be taken in the connections (cf. e.g. DE-OS 26 12 549).
From DE-OS 21 46 178 there is now known a thyristor on whose cathode side base area are provided several electrodes. An amplifying gate (auxiliary thyristor) directs currents free of the boundary layer over several ignition electrodes distributed over the upper surface of the thyristor to ensure a symmetrical ignition procedure. One of the amplifying gates of the ignited chief thyristor's output current will not suffice to start a corresponding thyristor connected in parallel.